A substantial body of literature exists regarding the relationships of primary amino acid sequence to serological idiotypy and binding site characteristics of antibodies. This data is enormously weighted to reflect the repertoires of the Balb/c and NZB mice, the only strains in which spontaneous and elicited plasmacytomas have been derived. The CBA/N mouse which has a linked defect in expression of anticarbonhydrate antibodies has been neglected in this regard, with only a single sequence of a hybridoma derived antibody published to date. This sequence demonstrated marked abnormalities in the pattern of VK, JH and DH segment utilization. We have assembled a panel of 200 unselected CBA/N B cell hybridomas for sequence analysis in order to investigate the role of combinatorial VDJH and VJK rearrangements in the expressed deficient repertoire of this strain of mouse. Conventional anti-hapten or anti-protein antibodies will also be sequenced to investigate the combinatorial diversity and idiotypic correlates of several new families of antibodies (anti-type III pneumococcal polysaccharide, anti (G)4, anti-insulin and anti-LPS) in which shared idiotypic serologic markers have been observed.